diff --git a/executables/nr-ru.c b/executables/nr-ru.c
index 21a62678cf399d1e7edd45e6c732301bbcc1d2f8..9abdd15192197b4494966920a99b1d9cb88a976b 100644
--- a/executables/nr-ru.c
+++ b/executables/nr-ru.c
@@ -717,6 +717,7 @@ void tx_rf(RU_t *ru,int frame,int slot, uint64_t timestamp) {
   NR_DL_FRAME_PARMS *fp = ru->nr_frame_parms;
   //nfapi_nr_config_request_t *cfg = &ru->gNB_list[0]->gNB_config;
   void *txp[ru->nb_tx];
+  char *print_test[ru->nb_tx];
   unsigned int txs;
   int i;
   T(T_ENB_PHY_OUTPUT_SIGNAL, T_INT(0), T_INT(0), T_INT(frame), T_INT(slot),
@@ -761,23 +762,27 @@ void tx_rf(RU_t *ru,int frame,int slot, uint64_t timestamp) {
     for (i=0; i<ru->nb_tx; i++){
       txp[i] = (void *)&ru->common.txdata[i][(slot*fp->samples_per_slot)-sf_extension];
     }
+print_test[0] = (char *)&ru->common.txdata[0][(slot*fp->samples_per_slot)-sf_extension];
+printf("txdata[0] = %d\n", print_test[0]);
 
 
     VCD_SIGNAL_DUMPER_DUMP_VARIABLE_BY_NAME( VCD_SIGNAL_DUMPER_VARIABLES_TRX_TST, (timestamp-ru->openair0_cfg.tx_sample_advance)&0xffffffff );
     VCD_SIGNAL_DUMPER_DUMP_FUNCTION_BY_NAME( VCD_SIGNAL_DUMPER_FUNCTIONS_TRX_WRITE, 1 );
     // prepare tx buffer pointers
     start_meas(&ru->tx_fhaul);
+printf("sending trx write from tx_rf\n");
     txs = ru->rfdevice.trx_write_func(&ru->rfdevice,
                                       timestamp+ru->ts_offset-ru->openair0_cfg.tx_sample_advance-sf_extension,
                                       txp,
                                       siglen+sf_extension,
                                       ru->nb_tx,
                                       flags);
+//printf("txp = %s\n", (char*)txp[0]);
     stop_meas(&ru->tx_fhaul);
     LOG_D(PHY,"[TXPATH] RU %d tx_rf, writing to TS %llu, frame %d, unwrapped_frame %d, subframe %d\n",ru->idx,
           (long long unsigned int)timestamp,frame,proc->frame_tx_unwrap,slot);
     VCD_SIGNAL_DUMPER_DUMP_FUNCTION_BY_NAME( VCD_SIGNAL_DUMPER_FUNCTIONS_TRX_WRITE, 0 );
-    AssertFatal(txs ==  siglen+sf_extension,"TX : Timeout (sent %u/%d)\n", txs, siglen);
+    //AssertFatal(txs ==  siglen+sf_extension,"TX : Timeout (sent %u/%d)\n", txs, siglen);
   }
 }
 
@@ -1446,7 +1451,7 @@ static void *ru_thread( void *param ) {
     if ((ru->is_slave) && (ru->if_south == LOCAL_RF)) do_ru_synch(ru);
 
     // start trx write thread
-    start_write_thread(ru);
+    ru->start_write_thread(ru);
   }
 
   pthread_mutex_lock(&proc->mutex_FH1);
@@ -2051,6 +2056,7 @@ void set_function_spec_param(RU_t *ru) {
       ru->fh_south_out           = tx_rf;                               // local synchronous RF TX
       ru->start_rf               = start_rf;                            // need to start the local RF interface
       ru->stop_rf                = stop_rf;
+      ru->start_write_thread     = start_write_thread;                  // starting RF TX in different thread
       printf("configuring ru_id %u (start_rf %p)\n", ru->idx, start_rf);
       /*
           if (ru->function == gNodeB_3GPP) { // configure RF parameters only for 3GPP eNodeB, we need to get them from RAU otherwise
diff --git a/openair1/PHY/defs_RU.h b/openair1/PHY/defs_RU.h
index 94afeed12f4561ffb4e9dd9c330189b191c094d8..1d1a7ca257829d516caaacce8e070402177b588c 100644
--- a/openair1/PHY/defs_RU.h
+++ b/openair1/PHY/defs_RU.h
@@ -538,6 +538,8 @@ typedef struct RU_t_s {
   void (*wakeup_prach_gNB)(struct PHY_VARS_gNB_s *gNB, struct RU_t_s *ru, int frame, int subframe);
   /// function pointer to wakeup routine in lte-enb.
   void (*wakeup_prach_eNB_br)(struct PHY_VARS_eNB_s *eNB, struct RU_t_s *ru, int frame, int subframe);
+  /// function pointer to start a thread of tx write for USRP.
+  int (*start_write_thread)(struct RU_t_s *ru);
 
   /// function pointer to NB entry routine
   void (*eNB_top)(struct PHY_VARS_eNB_s *eNB, int frame_rx, int subframe_rx, char *string, struct RU_t_s *ru);
diff --git a/targets/ARCH/USRP/USERSPACE/LIB/usrp_lib.cpp b/targets/ARCH/USRP/USERSPACE/LIB/usrp_lib.cpp
index 798b6b6b4d30b4360d46c6e9bc6b039bc429e905..33a4c71ede015467bd5499e315eb36a9b6b474b3 100644
--- a/targets/ARCH/USRP/USERSPACE/LIB/usrp_lib.cpp
+++ b/targets/ARCH/USRP/USERSPACE/LIB/usrp_lib.cpp
@@ -440,23 +440,25 @@ static int trx_usrp_write(openair0_device *device, openair0_timestamp timestamp,
       first_packet_state = false;
       last_packet_state  = true;
     }
-
+printf("~~~1 buff in usrp write = %d\n", buff[0]);
   pthread_mutex_lock(&write_thread->mutex_write);
-  write_thread->end = (write_thread->end + 1)% write_thread->num_package;
   end = write_thread->end;
+printf("package being write is %d\n", end);
   write_package[end].timestamp    = timestamp;
   write_package[end].nsamps       = nsamps;
   write_package[end].cc           = cc;
   write_package[end].first_packet = first_packet_state;
   write_package[end].last_packet  = last_packet_state;
   write_package[end].buff         = buff;
+printf("~~~2 write_package buff in usrp write = %d\n", write_package[end].buff[0]);
   write_thread->instance_cnt_write = 0;
+  write_thread->end = (write_thread->end + 1)% write_thread->num_package;
   pthread_cond_signal(&write_thread->cond_write);
   printf("trx_usrp_write signal end\n");
   pthread_mutex_unlock(&write_thread->mutex_write);
 
 
-  return ret;
+  return 0;
 }
 
 //-----------------------start--------------------------
@@ -474,7 +476,15 @@ void *trx_usrp_write_thread(void * arg){
   openair0_thread_t *write_thread = &device->write_thread;
   openair0_write_package_t *write_package = write_thread->write_package;
 
-
+    usrp_state_t *s;
+    int nsamps2;  // aligned to upper 32 or 16 byte boundary
+    int start;
+    openair0_timestamp timestamp;
+    void               **buff;
+    int                nsamps;
+    int                cc;
+    signed char        first_packet;
+    signed char        last_packet;
 
   while(1){
     pthread_mutex_lock(&write_thread->mutex_write);
@@ -483,23 +493,24 @@ void *trx_usrp_write_thread(void * arg){
       pthread_cond_wait(&write_thread->cond_write,&write_thread->mutex_write); // this unlocks mutex_rxtx while waiting and then locks it again
     }
     printf("signal unlock\n");
-    int start = write_thread->start;
-    printf("start = %d, end = %d\n", start, write_thread->end);
-    openair0_timestamp timestamp    = write_package[start].timestamp;
-    void               **buff       = write_package[start].buff;
-    int                nsamps       = write_package[start].nsamps;
-    int                cc           = write_package[start].cc;
-    bool               first_packet = write_package[start].first_packet;
-    bool               last_packet  = write_package[start].last_packet;
-    if(write_thread->end == (write_thread->start + 1)% write_thread->num_package){
+    s = (usrp_state_t *)device->priv;
+    start = write_thread->start;
+    printf("package bing use is start = %d, end = %d\n", start, write_thread->end);
+    timestamp    = write_package[start].timestamp;
+    buff         = write_package[start].buff;
+    nsamps       = write_package[start].nsamps;
+    cc           = write_package[start].cc;
+    first_packet = write_package[start].first_packet;
+    last_packet  = write_package[start].last_packet;
+    write_thread->start = (write_thread->start + 1)% write_thread->num_package;
+    if(write_thread->end == write_thread->start){
       write_thread->instance_cnt_write = -1;
     }
-    write_thread->start = (write_thread->start + 1)% write_thread->num_package;
     pthread_mutex_unlock(&write_thread->mutex_write);
     printf("end of write thread signal getting \n");
+printf("~~~2.5 write_package buff in thread = %d\n", write_package[start].buff[0]);
+printf("~~~3 buff in tx write thread= %d\n", buff[0]);
 
-    usrp_state_t *s = (usrp_state_t *)device->priv;
-    int nsamps2;  // aligned to upper 32 or 16 byte boundary
     #if defined(__x86_64) || defined(__i386__)
       #ifdef __AVX2__
         nsamps2 = (nsamps+7)>>3;
@@ -545,6 +556,7 @@ void *trx_usrp_write_thread(void * arg){
       ret = (int)s->tx_stream->send(buff_ptrs, nsamps, s->tx_md);
     } else ret = (int)s->tx_stream->send(&(((int16_t *)buff_tx[0])[0]), nsamps, s->tx_md);
     if (ret != nsamps) LOG_E(HW,"[xmit] tx samples %d != %d\n",ret,nsamps);
+printf("end of sending buffer in trx write thread\n");
 
     if(0) break;
   }